The Peruvian police at the Copacabana border seems to be fishing for bribes. They don't sell the SOAT insurance at the border. I got away with showing part of the policy of the Mercosur insurance (the part without that doesn't state the countries it's valid for), but some Germans in a RV weren't as lucky.

In Puno you can buy temporary SOAT (from La Positiva) at a small insurance broker, run by a very friendly woman:
Marlene Choque
Calle Deustua 299 (corner calle Arequipa)

The price scheme is a bit weird, I guess they upped the price for the 1 month because most travellers just buy a 1 month SOAT.
Prices:
1 month 90 Sol
2 months 100 Sol
3 months 150 Sol

The guy at Macara border post for Peru asked us if we had insurance. He did it such a way that it sounded to me like no paperwork would proceed until I showed him the insurance.
He also asked if I had bought insurance already or , do I have the "international " insurance?
I was quick on the thinking, as I almost pulled out my fake international insurance, actually I was reaching for it but then stalled and asked a few questions. He told us we can go across the road and buy insurance right at the end of the bridge, walk up the hill by the towers & look for the SOAT signs.
We were also able to buy just one month at $35 per bike. Perfect. If we stay longer we will just pull out the homemade document when ours runs out.
Only 20 or ten miles from the border we were stopped at a checkpoint and asked to show documents. FYI